Numerical Investigation of Single-phase Fully Developed Heat Transfer and Pressure Loss in Spirally Corrugated Tubes

Abstract

A numerical study is carried out to investigate heat transfer and friction argumentation in spirally corrugated tubes. 28 geometrically different tubes are investigated to cover a large set of different corrugation characteristics. The pipes investigated have pitch lengths l/D in the range 0.5 to 2.0 and pitch heights h/D in the range 0 to 0.16. Furthermore, the flow conditions defined by the Reynolds number are investigated for Re = 5000 and Re = 10000, resulting in a total of 56 Computational Fluid Dynamics (CFD) simulations . The performance of the heat exchangers are evaluated based on the Nusselt number, friction factor, and performance evaluation criterion coefficient combining the two into a single unique dimensionless parameter. The results suggest corrugation to be an effective way to increase the performance of tube heat exchangers. If only heat transfer is considered without paying attention to pressure loss, the optimal tubes have high corrugation heights, where the Nusselt number can be increased by a factor of 2 compared to the non-corrugated tube. If the performance evaluation criterion is used, the optimal geometry has a moderate corrugation height h/D between 0.05 and 0.10 and a low corrugation length l/D around 1.0, which can be explained by a high increase in pressure loss due to severe corrugation.